lock

Etymology 1

From Middle English lok, from Old English loc, from Proto-West Germanic *lok, from Proto-Germanic *luką from Proto-Indo-European *lewg- (“to bend; turn”). The verb is from Middle English locken, lokken, louken, from Old English lūcan, Proto-West Germanic *lūkan, from Proto-Germanic *lūkaną. Related to luxe via Latin.

noun

1. Something used for fastening, which can only be opened with a key or combination.
2. (computing, by extension) A mutex or other token restricting access to a resource.
   [T]he application must first acquire a lock on a file or a portion of a file before reading data and modifying it. 2005, Karl Kopper, The Linux Enterprise Cluster
3. A segment of a canal or other waterway enclosed by gates, used for raising and lowering boats between levels.
   Here the canal came to a check, ending abruptly with a large lock. 1846, William Makepeace Thackeray, Notes of a Journey from Cornhill to Grand Cairo
4. (firearms) The firing mechanism.
5. Complete control over a situation.
   Even though he had not yet done so, Jack felt he had a lock on the game. 2003, Charley Rosen, The Wizard of Odds
6. Something sure to be a success.
   Brian thinks she's a lock to get a scholarship somewhere. 2004, Avery Corman, A perfect divorce
7. (gambling) Synonym of Dutch book
8. (rugby) A player in the scrum behind the front row, usually the tallest members of the team.
   Ashton only had to wait three minutes for his second try, lock Louis Deacon setting it up with a rollocking line-break, before Romania got on the scoreboard courtesy of a penalty from fly-half Marin Danut Dumbrava. September 24, 2011, Ben Dirs, “Rugby World Cup 2011: England 67-3 Romania”, in BBC Sport
9. A fastening together or interlacing; a closing of one thing upon another; a state of being fixed or immovable.
10. A place impossible to get out of, as by a lock.
11. A device for keeping a wheel from turning.
12. A grapple in wrestling.

verb

1. (intransitive) To become fastened in place.
   If you put the brakes on too hard, the wheels will lock.
   We tiptoed into the house, up the stairs and along the hall into the room where the Professor had been spending so much of his time. 'Twas locked, of course, but the Deacon man got a big bunch of keys out of his pocket and commenced to putter with the lock. 1913, Joseph C. Lincoln, chapter 13, in Mr. Pratt's Patients
2. (transitive) To fasten with a lock.
   Remember to lock the door when you leave.
3. (intransitive) To be capable of becoming fastened in place.
   This door locks with a key.
4. (transitive) To intertwine or dovetail.
   with his hands locked behind his back
   We locked arms and stepped out into the night.
5. (intransitive, break dancing) To freeze one's body or a part thereof in place.
   a pop and lock routine
6. To furnish (a canal) with locks.
7. To raise or lower (a boat) in a lock.
8. To seize (e.g. the sword arm of an antagonist) by turning one's left arm around it, to disarm them.
9. (Internet, transitive) To modify (a thread) so that users cannot make new posts in it.
10. (Internet, transitive, Wikimedia jargon) To prevent a page from being edited by other users.
    Frequently-vandalized pages are generally locked to prevent further damage.
11. (intransitive, rugby) To play in the position of lock.
    Please don't disappoint me - you are female, aren't you? I have a lingering suspicion that you are 17 stone and lock for Tarankai. 1980, Ken Berry, chapter 14, in First Offender, Auckland: Collins, page 117

Etymology 2

From Middle English lok, lokke, from Old English locc (“hair of the head, hair, lock of hair, curl, ringlet”), from Proto-West Germanic *lokk, from Proto-Germanic *lukkaz, from Proto-Indo-European *lugnó-, from Proto-Indo-European *lewg- (“to bend”). Cognate with West Frisian lok, lokke, Dutch lok (“earlock, curl”), German Locke (“lock of hair, curl”), Danish lok, Swedish lock (“lock of hair, curl”). It has been theorised that the word may be related to the Gothic verb *𐌻𐌿𐌺𐌰𐌽 (*lukan, “to shut”) in its ancient meaning "to curb".

noun

1. A tuft or length of hair, wool, etc.
2. A small quantity of straw etc.
3. (Scotland, law, historical) A quantity of meal, the perquisite of a mill-servant.